P047-0011
MAVEN Observations of Ion Escape as a Function of the Twisted Tail Magnetotail Configuration

Friday, 11 December 2020
Poster
Peter Tatum1, Shannon Curry2, Janet G Luhmann3, Chuanfei Dong4, David Mitchell2, Gina A DiBraccio5, Jasper S Halekas6, James P McFadden7, Suranga Ruhunusiri8, Takuya Hara1, Shaosui Xu9 and Kathleen Gwen Hanley10, (1)Space Sciences Laboratory, Berkeley, CA, United States, (2)Space Sciences Laboratory, University of California Berkeley, Berkeley, CA, United States, (3)University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, United States, (4)Princeton University, Princeton, NJ, United States, (5)University of Michigan, Ann Arbor, MI, United States, (6)University of Iowa, Department of Physics and Astronomy, Iowa City, IA, United States, (7)Univ California Berkeley, Berkeley, CA, United States, (8)Department of Physics and Astronomy, University of Iowa, Iowa City, IA, United States, (9)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (10)Laboratory for Atmospheric and Space Physics, Boulder, CO, United States
Abstract:
Measurements from Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft are used to study the escape of atmospheric heavy ions—O+ , O2+, and CO2+—in the Martian magnetotail as a function of the upstream Interplanetary Magnetic Field (IMF) BY. By using the Solar Wind Ion Analyzer (SWIA) to determine 6000 orbits with pristine upstream solar wind measurements and taking corresponding Magnetometer (MAG) measurements of IMF configuration in conjunction with down-tail measurements of heavy ion flux using Suprathermal and Thermal Ion Composition (STATIC), we present large scale trends in the behavior of ion escape with respect to Mars’ twisted magnetotail configuration. We observed hemispheric asymmetry in the spatial distribution of escaping heavy ion flux depending on the upstream IMF configuration(+/-BY). In both cases, we find the population of escaping ions to be predominantly low energy (<30eV). We will also present data-model comparisons using magnetohydrodynamic (MHD) simulations, which agree with the data findings and also show a positive correlation between the abundance of closed field line topology and escaping particle flux, particularly where regions of closed field lines are adjacent to the current sheet. From the MHD simulations we can infer that closed field lines on the nightside of Mars contribute significantly to atmospheric escape, which contradicts previous suggestions that open field lines are the dominant escape route for atmospheric ions. Finally, we will compare the observed MAVEN escape rates for the +/-By tail configurations with the MHD simulated escape rates.
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